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#ifndef IMAGE_TRANSPORT__SIMPLE_SUBSCRIBER_PLUGIN_HPP_
#define IMAGE_TRANSPORT__SIMPLE_SUBSCRIBER_PLUGIN_HPP_

#include <functional>
#include <memory>
#include <string>

#include "rclcpp/subscription.hpp"

#include "image_transport/subscriber_plugin.hpp"
#include "image_transport/visibility_control.hpp"

namespace image_transport
{

/**
 * \brief Base class to simplify implementing most plugins to Subscriber.
 *
 * The base class simplifies implementing a SubscriberPlugin in the common case that
 * all communication with the matching PublisherPlugin happens over a single ROS
 * topic using a transport-specific message type. SimpleSubscriberPlugin is templated
 * on the transport-specific message type.
 *
 * A subclass need implement only two methods:
 * - getTransportName() from SubscriberPlugin
 * - internalCallback() - processes a message and invoked the user Image callback if
 * appropriate.
 *
 * For access to the parameter server and name remappings, use nh().
 *
 * getTopicToSubscribe() controls the name of the internal communication topic. It
 * defaults to \<base topic\>/\<transport name\>.
 */
template<class M>
class SimpleSubscriberPlugin : public SubscriberPlugin
{
public:
  virtual ~SimpleSubscriberPlugin() {}

  std::string getTopic() const override
  {
    if (impl_) {
      return impl_->sub_->get_topic_name();
    }
    return std::string();
  }

  size_t getNumPublishers() const override
  {
    if (impl_) {
      return impl_->sub_->get_publisher_count();
    }
    return 0;
  }

  void shutdown() override
  {
    impl_.reset();
  }

protected:
  /**
   * \brief Process a message. Must be implemented by the subclass.
   *
   * @param message A message from the PublisherPlugin.
   * @param user_cb The user Image callback to invoke, if appropriate.
   */

  virtual void internalCallback(
    const typename std::shared_ptr<const M> & message,
    const Callback & user_cb) = 0;

  /**
   * \brief Return the communication topic name for a given base topic.
   *
   * Defaults to \<base topic\>/\<transport name\>.
   */
  virtual std::string getTopicToSubscribe(const std::string & base_topic) const
  {
    return base_topic + "/" + getTransportName();
  }

  void subscribeImpl(
    rclcpp::Node * node,
    const std::string & base_topic,
    const Callback & callback,
    rmw_qos_profile_t custom_qos,
    rclcpp::SubscriptionOptions options) override
  {
    impl_ = std::make_unique<Impl>();
    // Push each group of transport-specific parameters into a separate sub-namespace
    // ros::NodeHandle param_nh(transport_hints.getParameterNH(), getTransportName());
    //
    auto qos = rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(custom_qos), custom_qos);
    impl_->sub_ = node->create_subscription<M>(
      getTopicToSubscribe(base_topic), qos,
      [this, callback](const typename std::shared_ptr<const M> msg) {
        internalCallback(msg, callback);
      },
      options);
  }

private:
  struct Impl
  {
    rclcpp::SubscriptionBase::SharedPtr sub_;
  };

  std::unique_ptr<Impl> impl_;
};

}  // namespace image_transport

#endif  // IMAGE_TRANSPORT__SIMPLE_SUBSCRIBER_PLUGIN_HPP_
